A vacuum insulation panel (hereinafter, vacuum insulation material) is manufactured by decompressing an encapsulant, which is comprised of a composite plastic laminate film exhibiting excellent gas barrier capabilities and receives an open cell hard plastic foam or an inorganic material as a core material therein, followed by heat sealing laminated gas barrier films along an edge thereof.
Generally, as air or moisture passes through a cover material or carbon dioxides or organic gas is generated therein, the vacuum insulation material undergoes gradual reduction in the degree of vacuum over time, thereby causing increase in thermal conductivity and thus making it difficult to maintain a high degree of insulation.
To solve such a basic problem, a vacuum insulation material in the art includes a core material, which is prepared by mixing a glass board generally prepared through a wet process, an organic binder and glass fibers.
Among these materials, glass wool provided to the vacuum insulation material provides excellent initial thermal capabilities, and thus is widely applied to electronic appliances, such as refrigerators, for reduction in power consumption.
However, when producing an 8 mm thick vacuum insulation material using such a glass wool material, it is necessary for the glass wool material to have a thickness of at least 80 mm or more.
As such, since it is difficult to insert such a thick glass wool material into a cover material in fabrication of the vacuum insulation material and handling of the glass wool material is also difficult, the glass wool material is thinly compressed before insertion into the cover material.
In a first compression method, glass wool is heated to a glass transition temperature and then compressed. In this case, since it is necessary to heat the glass wool to a temperature of 500° C. or more, this method requires a separate drying oven to maintain high temperature and excessively high equipment costs.
In a second compression method, a binder is used to promote coupling between fibers upon compression. In this case, although compression can be carried out efficiently, the vacuum insulation material can suffer from deterioration in thermal capabilities due to the binder.
As such, both methods in the art have problems in that the first method causes deformation of the glass wool and the second method does not permit reuse of the glass wool due to the use of the binder.
Moreover, in these methods, when the glass wool, that is, the core material, is inserted into the cover material, the fibers of the glass wool are brought into contact with film layers inside the cover material and thus cause damage to the cover material, thereby having undesirable effects on performance of the vacuum insulation material.